Potential impacts of enhanced tropical cyclone activity on the El Ni?o–Southern Oscillation and East Asian monsoon in the mid-Piacenzian warm period

热带气旋不仅是一种严重的灾害性天气事件,其在气候时间尺度也可通过加强海洋上层垂直混合进而调节全球海洋经向热量输送。基于一个海气耦合模式,本文探讨了强热带气旋活动对皮亚琴察暖期(又称晚上新世暖期;约300万年前)ENSO和东亚季风环流的可能影响。模拟结果表明,热带气旋引起的海洋垂直混合加强可造成热带东太平洋显著增温、温跃层加深,但ENSO年际变率减弱。对东亚季风而言,夏季副热带高压南移且西伸,副热带急流减弱并南移,我国南方西南风加强;冬季东亚大槽加深,副热带急流南移,我国北方偏北风加强。上述模拟结果可增进我们对热带气旋气候反馈作用以及晚上新世暖期全球气候特征的认识。     

The Relationship between the El Ni ?no/La Ni ?na Cycle and the Transition Chains of Four Atmospheric Oscillations. Part II: The Relationship and a New Approach to the Prediction of El Ni ?no

ABSTRACT The authors explored the connection and transition chains of the Northern Oscillation （NO） and the North Pacific Oscilla tion （NPO）, the Southern Oscillation （SO）, and the Antarctic Oscillation （AAO） on the interannual timescale in a companion paper. In this study, the connection between the transition chains of the four oscillations （the NO and NPO, the SO and AAO） and the El Nifio/La Nifia cycle were examined. It was found that during the transitions of the four oscillations, alternate anticyclonic/cyclonic correlation centers propagated from the Western Pacific to the Eastern Pacific along both sides of the equator. Between the anticyclonic/cyclonic correlation centers, the zonal wind anomalies also moved eastwardly, favoring the advection of sea surface temperature anomalies from the tropical Western Pacific to the Eastern Pacific. When the anti cyclonic anomalies arrived in the Eastern Pacific, the positive phase of NO/SO and La Nifia were established and vice versa. Thus, in 4-6 years, with an entire transition chain of the four oscillations, an E1 Nifio/La Nifia cycle completed. The eastward propagation of the covarying anomalies of the sea level pressure, zonal wind, and sea surface temperature was critical to the transition chains of the four oscillations and the cycle of E1 Nifio/La Nifia. Based on their close link, a new empirical prediction method of the timing of E1 Nifio by the transition chains of the four oscillations was proposed. The assessment provided confidence in the ability of the new method to supply information regarding the long-term variations of the ocean and atmosphere in the tropical Pacific.